Conventionally, an asphalt composition has been widely utilized for intended uses such as road pavement, a waterproof sheet, a soundproof sheet, and roofing. Upon the use of such an asphalt composition, many attempts have been made to add various polymers to the asphalt so as to improve the properties thereof. As such polymers, an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, rubber latex, a block copolymer consisting of conjugated diene and vinyl aromatic hydrocarbon, and the like have been used.
On the other hand, in recent years, from the viewpoint of cost reduction and the ease of paving, it has been increasingly desired to reduce a time required to produce an asphalt composition, to reduce the viscosity thereof, and the like.
In order to reduce the viscosity of an asphalt composition, a technique of allowing an asphalt composition to comprise various additives, so as to decrease a mixing temperature during the production thereof, has been known, for example, as described in Patent Documents 1 to 3.
For instance, a foaming agent has been added as an additive to such an asphalt composition, so that the production temperature has been decreased due to fine bubbles generated as a result of the addition of the foaming agent, or water has been added as an additive thereto, so that the asphalt has been liquefied. Otherwise, saturated fatty acid and phosphoric acid have been added, together with polybasic acid alcohol ester, to the asphalt composition, so that a decrease in the mixing temperature during the production has been studied.